Executing compiler command should include /unsafe param if it's compiling unsafe code

Trying out the coolest package ever on my codebase.
Found that unsafe will not compile

```
error CS0227: Unsafe code may only appear if compiling with /unsafe'
at FastScriptReload.Editor.Compilation.DotnetExeDynamicCompilation.ExecuteDotnetExeCompilation
```

Fixed at Assets\FastScriptReload\Scripts\Editor\Compilation\DotnetExeCompilator.cs by adding /unsafe flag


BTW I am using Unity 6 and everything works fine. Your are the GOAT hehe